Battery Storage Systems
Why add a battery to solar panels
Solar panels make most power at midday. Most homes use more in the morning and evening. Without storage, the spare midday power goes to the grid at the export rate, while a battery keeps it so you can use it after dark.
That shift can cut the power you buy. However, a battery also costs money, so the gain depends on how much you use and what you pay per unit. Our guide to solar battery value covers the sums.
How a solar battery works
- Panels make direct current during the day.
- The inverter converts it to alternating current for your home.
- Spare power charges the battery instead of leaving for the grid.
- When demand rises in the evening, the battery discharges to meet it.
- Only when the battery runs low does your home draw from the grid.
Some batteries also charge from the grid overnight on a cheap tariff. That can help if you have a smart tariff, because you store cheap power and use it at peak times. Check that your tariff allows it before you buy.
New system or retrofit
You can fit a battery with new panels or add one later. A combined install can use a single hybrid inverter, so it often saves labour and equipment. A retrofit works too, either with a hybrid inverter swap or an extra AC-coupled unit.
Retrofits need care because the new equipment must work with your current inverter. Ask the installer to confirm that your Smart Export Guarantee registration stays valid. Batteries also qualify for the temporary zero rate of VAT in Great Britain until 31 March 2027.
What to check before you buy
Compare usable capacity rather than headline capacity, because some of the stored energy stays in reserve. Check the warranty length and the number of charge cycles it covers. Also ask how the battery behaves in a power cut, since not every model keeps the lights on.
Size matters as well. A battery that is too big may never fill in winter, while a small one leaves spare solar unused in summer. A good installer models your own meter data before recommending a size.
Who benefits most
Homes with high evening use, electric heating or an electric car gain the most. You can read how a charger fits in on our page about EV charger installation. Homes that are empty all day also export more, so storage gives them more to save.
Storage is available through installers in every city we list. See, for example, solar panels in Manchester and solar panels in Birmingham. Installers can combine it with solar panel installation in a single visit, which often saves scaffolding costs.
Battery Storage Systems: common questions
Can I add a battery to an existing solar system?
Yes, because most systems can take a battery through a hybrid inverter or an AC-coupled unit. Ask your installer to confirm that the work keeps your MCS paperwork and export registration valid.
Do I need a battery to get paid for exporting solar power?
No. The Smart Export Guarantee pays for the power you export, whether or not you own a battery. A battery lets you use more of your own power instead, which can save more.
What happens to a solar battery in a power cut?
It depends on the model. Many batteries shut down with the grid for safety, so you need a unit with a backup feature if you want power during an outage.
How long does a home battery last?
Warranties often run for about ten years, although the real life depends on use and the model. Check the warranty terms and the cycle count before you buy.
Ready to talk about battery storage systems?
Tell us about your property and we will pass your enquiry to MCS-certified installers who cover your area.